In tape automated bonding (TAB), the pads of an IC and the leads of a tape are simultaneously connected with all pins according to tape assembly bonding, thereby achieving quite high connecting efficiency for an IC having multiple pins. A TAB package is called a tape carrier package (TCP) and characterized by a small size, a small thickness, and a light weight. A tape used for TAB is called a tape carrier (film carrier). Further, the sprocket holes of a tape and its associated standards are based on American film standards. The manufacturing process of three-layer tapes started from a 350-μm pitch and 40 pins (calculator) and has become finer year by year. The appearance of a thermal head in 1983 has achieved finer pitch at a high pace. Fine pitch is currently led by LCD drivers.
Referring to FIGS. 15 to 19, a method of manufacturing a conventional film carrier will be described below.
FIG. 15 is a diagram showing a process of forming holes on the conventional tape carrier. FIG. 16 is a diagram showing a process of applying photoresist on the conventional tape carrier. FIG. 17 is a diagram showing a process of forming leads on the conventional tape carrier. FIG. 18 is a diagram showing a packaging process on the conventional tape carrier. FIG. 19 is a diagram showing the conventional tape carrier.
First, in FIG. 15, device holes 3 and sprocket holes 2 are formed by die-cutting a film 1 (polyimide, epoxy containing glass, or the like) acting as a base material. Then, in FIG. 16, copper foil 4 is bonded to the film 1, on which the device holes 3 and the sprocket holes 2 have been formed as shown in FIG. 15, while being pressure welded by heat rollers, and photoresist is applied to both surfaces of the film 1. Then, in FIG. 17, mask exposure, development, and etching are performed to form a wiring pattern on the film 1, so that leads 6 are formed protruding from the device holes 3 of the film 1, the device holes 3 having been formed as shown in FIG. 15. Unnecessary resist is removed and Sn plating and Au plating (primary plating) and solder plating (primary Ni plating) are performed on the surfaces of the leads, so that a film carrier process is completed.
The film carrier has a length of 20 to 60 m and the film carrier process is continuously performed on the long film. At the completion of all the processes, the film is wound on a reel via spacers and sent to the subsequent process. Mainly two kinds of pump forming processes are available which include a method of forming bumps on a chip and a transfer bump method of forming bumps on the side of leads. In a typical bump forming method, barrier metal is formed on the pads of a semiconductor chip and bumps are formed thereon by plating method, which is the most widely used. The packaging process of FIG. 18 includes an inner lead bonging (ILB) process in which the leads 6 and the electrodes of the semiconductor chip 7 are connected via the bumps, resin is then applied thereon, and the semiconductor chip is sealed. Thereafter, electrical characteristics are measured using measuring terminals formed on the tape and finally the tape is cut according to the predetermined dimensions of a product area 8.
The inner lead pitch of the TCP started from a 350-μm pitch and 40 pins (calculator) and has become finer year by year. The appearance of a thermal head has achieved finer pitch at a high pace. Fine pitch is currently led by LCD drivers. In recent years, LCD panels have become larger and LCD drivers have had more output terminals. An LCD driver is divided into an input side for digital data of images, a power supply, a control signal, and so on and an output side for output to a panel. More pins have been provided for output signals and output terminals have been aligned with finer pitch in response to high power in recent years.
FIG. 19 shows a semiconductor package of a TAB tape for the conventional tape carrier package formed as shown in FIG. 18. Reference numeral 60 denotes input terminal wires and reference numerals 61, 62, 63, and 64 denote leads acting as output terminal wires. Further, the terminal wires are connected to input test pads 60Tp and output test pads 61Tp, 62Tp, 63Tp, and 64Tp for inspecting the electrical characteristics of products. An electrical inspection is conducted by bringing probes into contact with the test pads. In the case of wires connected from the input/output terminals with finer pitch, the test pads are larger than the wires and thus the test pads cannot be aligned in a single line. In order to avoid this problem, the output test pads 61Tp, 62Tp, 63Tp, and 64Tp are aligned in several lines to secure a test pad area. In this way, fine pitch causes a large test pad area on the TCP, increasing the cost of the package.
One solution is disclosed in Japanese Patent Laid-Open No. 8-24586. As shown in FIG. 20 of a conventional tape carrier with a reduced terminal area, since the number of test pads is smaller on the input side of a TCP package, input test pads 67 on a tape are moved to the upper side or lower side with the minimum pitch, and the input terminals of two semiconductor chips 65 and 66 are placed to face each other, so that a layout area can be shared by input test pads 67 and 68 of the two chips on the tape and each TCP can be miniaturized.